The move comes as U.S. auto safety regulators investigate complaints of exhaust fume problems in more than 1.3 million Explorers from the 2011 through 2017 model years. In Austin, more than 60 officers have reported health problems since February and more than 20 were found to have measurable carbon monoxide in their systems, city officials said Friday.

The National Highway Traffic Safety Administration has found more than 2,700 complaints of exhaust odors in the passenger compartment and fears of carbon monoxide in an investigation started a year ago. Among the complaints were three crashes and 41 injuries, mostly loss of consciousness, nausea and headaches. Many of the complaints came from police departments, which use the Police Interceptor version of the Explorer in patrol fleets. Police complaints included two crashes with injuries and one injury allegation due to carbon monoxide exposure.

In a memo obtained by ABC13, the Harris County Sheriff's Office said it currently has 56 potentially impacted Ford Explorers in its fleet. Chief Deputy E. Toquica said one deputy has reported symptoms consistent with carbon monoxide exposure and that all potentially impacted Explorers have been outfitted with carbon monoxide alarms.

Houston Police Chief Art Acevedo said none of his officers have reported carbon monoxide poisoning and that he would "continue to monitor" the situation.

While several large police departments have been aware of the issue and installed carbon monoxide detectors in their vehicles, Austin appears to be first major city to pull large numbers of police Explorers off the road.

Ford spokeswoman Elizabeth Weigandt said the company is working with police, customers and NHTSA to investigate the reports and solve problems.

"Safety is our top priority," Weigandt said.

The decision by Austin police left the city scrambling to find replacement cars for more than half of its patrol fleet.

The Police Department said it will move equipment from the Explorers to about 200 Ford Taurus and Crown Victoria models, many of which will be unmarked, and have them ready for patrol ready by Monday. Interim Police Chief Brian Manley said Austin will have just as many officers on patrol, but that they will ride in pairs. The city will closely track response time to emergency calls.

"There will a concern there will be a spike in crime," Manley said. "But for those criminals who think they can take advantage of the circumstances, remember we now have a whole fleet of unmarked vehicles on patrol."

The city installed carbon monoxide alarms after officers began reporting getting sick while in the vehicles, and parked 60 of them when the alarms activated. Of the 20 officers found to have elevated levels of carbon monoxide, three have not been able to return to work.

The NHTSA has said nearly 800 people have complained to the government about fumes, while Ford has received more than 2,000 complaints and warranty claims. The agency tested multiple vehicles at its Ohio research center, and made field inspections of police vehicles involved in crashes. As of Thursday, the agency had found no evidence or data to support claims that injuries or crash allegations were caused by carbon monoxide poisoning. The agency said it had early tests that suggest carbon monoxide levels may be higher in certain driving conditions, but the significance and effect of those levels remain under investigation.

The NHTSA also said that the Police Interceptor version of the Explorer is experiencing exhaust manifold cracks that are hard to detect and may explain exhaust odors. Investigators will evaluate the cause, frequency and safety consequences of the cracks, and whether Explorers used by civilians are experiencing cracked manifolds, the agency said.

"There have been a number of police departments that have looked at this problem. Most have not had (Austin's) experience and those that have had issues have been able to resolve them," said Darrel Stephens, executive director of the Major Cities Chiefs Association. "I have not heard of any other department having the number of problems that Austin is experiencing."

Sean Kane, president of Safety Research and Strategies Inc., a Massachusetts firm that does auto testing for plaintiffs' lawyers and other clients, said he expects other law enforcement agencies will now check their patrol fleets and may face the same dilemma as Austin about how to maintain patrols.

"It's not an easy decision whether you're a large city or small town," he said.